A man walks through St Peter's Square at the Vatican on Monday afternoon, the eve of the start of the conclave to elect a successor to Pope Benedict XVI.

Canadian Cardinal Thomas Christopher Collins walks through St Peter's Square at the Vatican, after the cardinals' final general congregation.

Canadian Cardinal Thomas Christopher Collins is surrounded by police and security as he walks through St Peter's Square

German cardinal Walter Kasper walks through St Peter's Square at the Vatican, after the cardinals' final general congregation meeting on Monday afternoon, the eve of the start of the conclave to elect a successor to Pope Benedict XVI.

Nigerian cardinal John Onaiyekan walks through St Peter's Square

Canadian Cardinal Marc Ouellet walks through St Peter's Square at the Vatican

Canadian Cardinal Marc Ouellet walks through St Peter's Square at the Vatican

Nuns from Mexico walk through St Peter's Square at the Vatican on the eve of the start of the conclave to elect a successor to Pope Benedict XVI.